Fix the startup script so that it can accept option arguments. This fixes
a problem with starting Mozilla from the KDE dock if another instance of
Mozilla is already running.
Tested by: Vivek Khera <vivek@khera.org>
Approved by: portmgr (kris)

Make the Mozilla startup scripts a little smarter. Instead of launching a
new Mozilla instance each time, check to see if one already exists, and if
so, spawn a new browser tab in the current window.
PR: 45610
Submitted by: Nick Jennings